1. Field of the Invention
This invention relates to fail safe electrical receptacles, more particularly, a fail safe electrical receptacle that provides power to an outlet only when a standard electrical plug is inserted into the outlet and the first blade entry makes contact with a neutral contact which then allows for the second blade to make contact and complete the circuit. Specifically, the instant invention electrical plug is energized when it causes at least two pairs of contacts to be coupled on a live side of the circuit which in turn engage a neutral contact that in turn couples to and is energized by a second set of an at least four pairs of contacts through the second prong that completes the circuit. Failure to engage the contacts results in no energization of the plug and engaging only the first set of the at least two contacts only engages the neutral contact, not completing the circuit resulting in no injurious shock.
2. Background of the Invention
Oftentimes, accidents occur in the home due to children inserting objects into power receptacles. If the child is lucky, he or she receives only a minor shock and learns to never insert anything other than an electrical plug into a power receptacle. However, more often than not, a child receives a severe shock, which may not only cause physical and psychological damage to the child, but may also cause physical damage to the home.
In order to help reduce the amount of these types of accidents in the home, a wide range of receptacle safety devices have been invented and used. For instance, the most common method of child safety proofing a receptacle is by inserting plastic safety plugs into an unused outlet. Although the outlet covers do provide protection, oftentimes the adults forget to reinsert the covers after using the outlet, thereby exposing the live outlet to the children.
In addition, a wide variety of shock resistant electrical outlets have been invented wherein power is not provided to the outlet unless the internal switches are triggered, via electrical plugs or other object, to an on position. In many instances, however, children become creative and insert two different foreign objects into the receptacle at once, thereby turning on both internal switches to complete a circuitry loop, resulting in the child getting shocked. That is, the circuit becomes hot from a non-standard plug blade or object that engages the internal switches.
In many circuits that require contact from the plug blade, the circuit setup activates when either blade is entered, thus a single blade is sufficient to complete the circuit. In theses instances, even though the fact that contacts need to be made viz a vis insertion of a single metallic object that might trip the contact points or switches. This can possibly lead to the completion of the circuit with a single prong like object. That is the circuit can go live as it does not complete the circuit through coupling of each side or prong side of the terminal to a set of neutral contacts first. Put another way, none of the existing devices require one prong to energize the other. Even in those that require both blades, there still exist scenarios in which non-standard single blade like device or two such non-standard blade like devices, like tweezers, could complete the circuit by completing contacts on either side of the receptacle.
Many of these existing designs rely on a circuit interrupter or similar device to trip and break the circuit. One mode in which these devices might fail is where insertion of the blade like object results in energization of the circuit and the breaker fails. The inclusion of breakers and similar devices also adds cost and complexity to the receptacle. Even in the embodiments that utilize switched circuits using the plug blade to complete a connection, as noted, these connections can be unsafely made. Thus, there exists the need for a receptacle which provides power or goes “hot” to only when a standard electrical plug is inserted into the outlet in both blade slots.
There are several examples of relevant patents on prior designs, these include the following patents:
U.S. Pat. No.InventorIssue/Pub. Date7,045,723ProjkovskiMay 16, 20062004/0067692Chevarie et al.Apr. 8, 20042003/0124893CampbellJul. 3, 20032003/0085108Chiang et al.May 8, 20032003/0045145Mortun et al.Mar. 6, 20032002/0104745AllisonAug. 8, 20026,455,789AllisonSep. 24, 20026,111,210AllisonAug. 29, 20005,387,761SimonisFeb. 7, 19955,267,870MareshDec. 7, 19935,113,045CroftonMay 12, 19924,995,017Sellati et al.Feb. 19, 19914,951,732NeuenschwanderMay 27, 19864,867,694ShortSep. 19, 19894,271,337BarkasJun. 2, 19814,168,104BuschowSep. 18, 19793,846,598MucsiNov. 5, 1974
With respect to U.S. Pat. No. 7,045,723 to Projkovski, the instant invention is a direct improvement in that it provides for safe operation without the need for a breaker and reduces the complexity of the device. The switches in the Projkovski patent do not engage in the manner herein described. There are additional switch elements, some of which are closed by default, and/or a breaker element to provide for the safety aspects in the receptacle and prevent the device from inadvertently becoming live. In contrast, the instant invention utilizes only open contacts, does not require a breaker to provide safer operation and can be manufactured at more easily and at a lower cost.
Although the prior art discloses many safety electrical receptacles, none has the same structure and operation as the present invention. None provides the positively claimed electrical coupling of an at least one pair of contacts on a live side to neutral and then another pair of contacts to the neutral on a neutral side to complete the circuit, the contacts only being engaged if a standard sized plug blade or prong is entered into the outlet and the circuit only being complete with two such standard blades.